Device and method for purifying and recycling shower water

ABSTRACT

The present invention describes a hybrid device ( 1 ) for a recirculation shower, allowing purification and either recycling of water or discarding of water, wherein said hybrid device ( 1 ) comprises a recirculation loop ( 2 ), a filter system ( 4 ) with a nano-filter ( 5 ) such as for instance an electropositive nano-ceramic filter, e.g. a nano alumina (fiber) filter, at least one filter quality sensor ( 3 ), at least one pre-filter ( 6 ), and wherein the hybrid device ( 1 ) is arranged to redirect the water from recirculation to drainage when the at least one filter quality sensor ( 3 ) indicates the need thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/367,772, filed on Jun. 20, 2014, which is the National Phase ofInternational Application No. PCT/SE2012/051430, filed on Dec. 19, 2012,which claims priority to Sweden Patent Application No. 1151272-0, filedon Dec. 23, 2011, and the disclosures of each of the above isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a shower concept that involves optionaland optimized recirculation of water combined with verifiedpurification, thereby providing an economically and environmentallycompetitive alternative.

BACKGROUND

It is known to both recycle and filter water in shower systems. Forexample in US2011225722 there is disclosed a device for distribution ofshower water in a closed circuit. The device includes an element forclosing the outlet for draining the shower pan and an intake elementincluding an intake pump able to draw in water from the shower pan,filter it and feed it back, via the water redistribution element to theelement suitable for spraying the water. Further, SE469413 describes ashower comprising at least one nozzle through which a fluid flows in ashower cabin. The shower shows a collection container for said fluid,and a nozzle and said container are part of a circulation circuitcomprising a pump, aiding said fluid in said container to circulatethrough said nozzle. The shower also shows means to discard said fluid.In US 20110146800 a water recycling apparatus and fluid contaminationdetection system is disclosed. This system comprises optical means fordetecting contaminants, a filter for purification and may also include adisinfection unit. Furthermore, in US20100237021 a recirculation showerfor aircrafts or other transportations is disclosed. This devicecomprises backwash lines. A first backwash line, designed to conveybackwash water to the filtration unit and a second backwash linedesigned to discharge backwash water from the filtration unit. Thepurpose of the arrangement is to minimize the use of freshwater.

There are several drawbacks to the methods and devices described inthese documents. Firstly, there is no means for providing a user with ashower experience equal to that of a conventional shower. Furthermore,the shower described in SE469413 place a heavy burden of control andmaintenance on the user and is not very user-friendly. The cabin inUS2011225722 does not provide user-important options. In bothUS2011225722 and SE469413 there is no way of knowing if the device orsystem is operating in a satisfactory way. This leaves an unsolved issueof hygiene. Moreover, in US2011225722 the water is passed through afiltering means, preferably a grid filter or sieve. This leads to apotential problem with bacterial growth and recirculation ofcontaminated water as a result. Furthermore, SE469413 and US20110146800disclose a water container under the drain in the shower cabin where thewater that is to be recirculated is contained. The containedcontaminated water implies the potential risk of bacterial growth andviral spreading along with odour and risk for place of residence forvarious pests. Neither the backwash function, disclosed inUS20100237021, discloses any means for verifying the quality of thefilter post backwashing. This also, as previously mentioned, indicatespotential problems with bacterial growth and viral spreading along withodour and risk for place of residence for various pests. Furthermore,both US20110146800 and US20100237021 disclose an optional use ofdisinfectants. The use of substances with disinfecting qualities inthese systems, indicate an increased risk for hypersensitivity andvarious allergies. Further, several of the known arrangements useoptical detection with potential problems with bubbles during thedetection. When the water is flowing in the system turbulence is knownto occur which produce bubbles that make optical measurements moredifficult. Yet another drawback is experienced when any of the previousinventions malfunctions. It can for example be malfunctions regardingthe filter components or the pump system. The user is then left with noshower options.

One aim of the present invention is to provide a shower solutionensuring that the user receives an equally comfortable andnon-complicated shower experience as in a conventional shower. Anotheraim of the present invention is to ensure the quality of said showerexperience. Yet another aim of the present invention is to provide aneconomically and environmentally friendly option to existing showeralternatives.

SUMMARY

The purpose above is achieved by a hybrid device allowing purificationand either recycling of water or discarding of water, wherein saidhybrid device comprises a recirculation loop, a filter system with anano-filter, at least one filter quality sensor and at least onepre-filter positioned before the nano-filter in process terms, andwherein the hybrid device is arranged to redirect the water fromrecirculation to drainage when the at least one filter quality sensorindicates the need thereof.

Said hybrid device according to the present invention enables users toreceive an equally comfortable shower experience as in a conventionalshower. The present invention allows both wash and rinse actions,implying that the water may be purified and recirculated until the waterpassing the system is at a pre-determined maximum level of contaminants.Said hybrid device comprises at least one water quality sensor thatindicates the need of drainage. In such a case, the hybrid devicediscards the contaminated water. Therefore, the hybrid device accordingto the present invention ensures a predecided quality of water for theuser.

Said filter system of the hybrid device according to the presentinvention ensures a high quality of the water recycled. The presentinvention comprises a filter system with a nano-filter such as forinstance an electropositive nano-ceramic filter, e.g. a nano alumina(fiber) filter and at least one filter quality sensor. According to onespecific embodiment, the nano-filter is a nano alumina (aluminium oxide)filter. The use of a nano-filter, such as a nano alumina filter, alsoimplies the use of greater flow rates and the clogging resistance isalso greater than equivalent performing membrane filters. Waterpurification based on nanotechnology implies purification on a virallevel. In one specific embodiment of the present invention the hybriddevice comprises a nano alumina filter comprising aluminium hydroxidefibers. The fibers may e.g. be about 2 nanometer in diameter. They arehighly electropositive. When dispersed in water they may retainelectronegative particles. The nano-filter incorporated in the hybriddevice according to the present invention filters bacteria and nano sizeparticulates, such as viruses. According to the present invention, thenano-filter enables filtering of e.g. intestinal bacteria, such as E.coli, and intestinal/abdominal parasites, which is of importance inrelation to purification of water and of course showering. Also othercontaminants are of course filtered off by the nano-filter incorporatedin the device according to the present invention. The filteringaccording to the present invention is also preferred in terms of removalof contaminants when being compared to other methods like the use of anUV filter or pasteurization where the contaminants are neutralized butnot removed. These methods may give a harmless water, but the taste andsmell may still be undesirable.

Furthermore, combining said nano-filter with at least one filter qualitysensor in a filter system ensures that said filter system is running asexpected and in an optimal manner.

Moreover, shower users have grown accustomed to showers with a high flowrate and combining said filter system in the present invention ensuressaid flow rate providing an equally comfortable shower experience as ina conventional shower. Moreover, other advantages according to thepresent invention are the high level of comfort and the high level ofautonomy of the system, not being affected by other water usage in e.g.a household, for instance in relation to temperature fluctuations. Thecomfort according to the invention may for instance be based ondifferent criteria, such as water flow and water pressure, the waterquality, and the temperature as well as fluctuations thereof.Furthermore, the device system according to the present invention mayalso ensure a stabilized pressure/flow in e.g. a shower.

Furthermore, the present invention provides an option of a conventionalshower experience, thereby being a hybrid device. This is one advantagewith the present invention, if for example there is a malfunction, theuser can still enjoy a shower. This provides the user with aneconomically, user- and environmentally friendly option to existingshower alternatives.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one embodiment of the hybrid device according to thepresent invention.

FIG. 2 shows one example of a flow chart for the shower concept of thepresent invention.

SPECIFIC EMBODIMENTS OF THE INVENTION

Below, specific embodiments of the present invention are described. Thepresent invention is a hybrid device since it provides the user bothwith a recirculation shower and with an ordinary shower. The wordingordinary shower indicates a system with incoming new water and allowingthe same water to exit directly after use into the drainage system.Furthermore this hybrid device is automatically set to recirculationwith drainage, when one of the indicators notifies the need to do so,but as a hybrid device is equipped with an option to set the systemmanually in ordinary shower mode. Another advantage with therecirculation mode according to the present invention is the highensured level of clean water, even when being compared to regular showerwater used today. For instance, contaminants like increased metalamounts, contaminants from fouling, depositions, bacteria likelegionella bacteria, etc. are common in warm water piping used in manywater systems for households. Such contaminants may be removed by thesystem according to the present invention. This may in fact also open upfor the possibility of showering with an open mouth in countries wherethis is not suitable today.

According to one embodiment, the hybrid device according to the presentinvention comprises a recirculation loop, a filter system with anano-filter and at least one filter quality sensor, and wherein thehybrid device is arranged to redirect the water from recirculation todrainage when the at least one filter quality sensor indicates the needthereof. Said filter quality sensor may be a pressure meter, a pressureswitch or a flow meter but it can also comprise a combination of both.In one specific embodiment of the present invention, said filter qualitysensor may be an advanced flow meter, and in another specific embodimentof the present invention, said filter quality sensor may be a digitalpressure meter, but also other kinds of similar means are possible. Whensaid at least one filter quality sensor is embodied as a pressure meter,a pressure drop indicates an initially full filter. Said filter is stillperforming purification at a pre-determined level, but this is an earlyindication that a replacement of said filter needs to take place.Further, when said at least one filter quality sensor is embodied as aflow meter, a decreased flow indicates, as mentioned above, that areplacement of said filter needs to take place. In one embodiment of thepresent invention, said at least one filter quality sensor is positionedbefore the pre-filter, in process terms. In process terms implies thatthe water passes said filter quality sensor before it passes thepre-filter. In another embodiment said at least one filter qualitysensor is positioned after the pre-filter and before the nano-filter, inprocess terms. In yet another embodiment of the present invention, saidat least one filter quality sensor, is positioned after the nano-filterin process terms. One advantage, of an indication from at last onefilter quality sensor, is reassurance that the system is operating asdesired. Another advantage, of said at least one filter quality sensor,is a lengthened lifetime of said filter system.

Said nano-filter in the present invention utilizes electron adsorptionas means for purification, and the electropositive fibers adsorbsvarious sorts of particles, such as silica, metals, bacteria and virus,but also other sorts of particles. One advantage in the presentinvention, in comparison with SE469413 or US2011225722, is the abilityto purify water at a viral level. US2011225722 implies a filtration oflarge particles, and SE469413 implies a filtration of large particlesand bacteria. Neither US2011225722 nor SE469413 discloses prevention ofspreading of virus.

Another embodiment of the present invention comprises more than onenano-filter coupled in series or parallel. Further, an attempt toreplace existing filters in existing showers, with a nano-filter, wouldnot be enough to achieve the present invention.

According to another embodiment, the hybrid device according to thepresent invention comprises at least one pre-filter, positioned beforethe nano-filter in, process terms. Standard filters may be used for thisstep, such as e.g. activated carbon filters, UV-filters, nylon filtersor yarn-wound filters, but also other kinds of similar means arepossible, such as e.g. ion exchange technique, comprising a back flushoption to decrease the need for deliming.

It is important to understand that any type of filter technique may bepossible to use in the pre-filter according to the present invention,and only examples are disclosed above. For instance, besides the onesdisclosed above, also a wide-meshed filter, such as a mechanical filter,only filtering off very large particles may be used as the pre-filter.As said, many other types are also possible.

The use of different filters often implies different intended purposes.This may for example be to remove larger particles, such as hair andsand or smaller contaminants, such as humus, chlorine or bacteria, butis not restricted to these examples exclusively. Different contaminantsset different requirements on selected filter. One advantage, with atleast one pre-filter, is a lengthened lifetime of the often moreexpensive nano-filter. Another advantage is the option to adjust thehybrid device to current water quality. Different soil type meansdifferent water quality, and thereby different requirements set on thehybrid device. The present invention, installed in regions with highlevels of lime water and calcareous water, may require a wetting filterwhile a hybrid device installed at places where the water is soft, maynot need said filter. Further, said hybrid device, installed in aprivate facility may only require a filter separating from sand andhair, and then a yarn wound filter may be sufficient. If for example thepresent invention is installed in a place where there is an issue withhummus, an active carbon filter may be the optimal choice.

As mentioned above, there are different filters that may be used in thepresent invention. In one embodiment of the present invention, acombination of different filters may be used. These filters may behoused in one or more filter housing(s). One advantage, with said filterhousing(s), is an option of containing different types of pre-filtersand combining said pre-filters. This may, as hinted above, allow thepresent invention to be optimized, according to requirements set by theexisting water type, at the intended location of where the hybrid deviceis to be installed.

In yet another embodiment of the present invention, said filterhousing(s) can be modified. Said modified filter housing(s) may consistof a built in flow meter that is replaced along with said filter, whensaid filter quality sensor indicates the need thereof. One advantage isthe option of continuous development and optimization of said filtertype by the shower manufacturer. Another advantage is facilitatingfilter exchange. Neither SE469413 nor US2011225722 discloses anythingthat may facilitate maintenance. Filter housings of today imply that askilled person need to perform the replacement of filters, but saidfilter housing(s) according to the present invention, with a built inflow meter, implies a design that allows facilitated filter replacement.One embodiment of said filter housing(s), with a built in flow meter,may allow a filter replacement through a two step button push.

In another embodiment of the present invention, said hybrid devicecomprises a water container. The water quality is further ensured bysaid water container only containing pure water. This is different incomparison to the solution disclosed in SE469413, where contaminatedrinse water is kept in the container. Said water container according tothe present invention, holding clean water, prevents issues withbacterial growth, spreading of virus and provides a low maintenance.Further, said water container comprises a level sensor that indicates alow level of water and a level sensor that indicates a high level ofwater, and wherein the hybrid device is arranged to allow new water toflow in to said water container, when the level sensor indicates theneed thereof. This further ensures a steady flow within the system.

In one specific embodiment of the present invention, the water containermay be about 10 L, but containers in the range of 8-30 L, dependent uponthe intended use, may be of interest. Also smaller water containers,even below 2-3 L and even down to 0.5 L, and larger water containers maybe possible according to the present invention. In for example asubmarine, where a large group is to use the same shower, a largercontainer may be preferred and continuous showering applied.

In one embodiment of the present invention, said hybrid device comprisesa flow through water heater. This is different from SE469413, whichdiscloses a heat coil. A heat coil may be suitable for small volumes ofwater and low flow rates, but may pose a problem today, when acomfortable shower require a flow rate of 9-20 l/min for approximately6-8 minutes. The present invention utilizes, in one embodiment, a flowthrough heater in combination with a water container, which ensuresrequired flow rate and a pleasant temperature. In one specificembodiment of the present invention, the flow through water heater has apower of about 6.5 kW and a water container volume of about 10 L.

It should be noted that the heating system of the present invention mayembody different units and be of different type. For instance, a heatingcoil such as above is possible, but a heat exchanger or a systemthereof, is another possible alternative. Other possible examples areheating with electric heater like a heating cartridge, and heatexchanging by the use of tap hot water. The latter alternative may bebeneficial as there is no need for e.g. an extra power supply, howeverthe water consumption and also the energy consumption may be high.Another possible example is heating with other types of media, such ase.g. liquefied petroleum gas (LPG). Moreover, the regulation of theheating system may vary, e.g. an ordinary thermostat or several suchtemperature regulator units may be incorporated.

In yet another specific embodiment of the present invention, a mixer tapin contact with the water inlet may be used. This indicates further costefficiency if a household for example has both warm and cold fresh waterpiping. Further, said mixing tap may reduce the size of the hybriddevice.

One advantage with the present invention is that it can be installed indifferent places. In one embodiment of the present invention, saidhybrid device may be installed in a shower cabin. In another embodimentof the present invention, said hybrid device may be connected to theregular water pipes in a house, and built in to the wall and/or floor.In yet another embodiment of the present invention, said hybrid devicemay be partially built in to the wall and/or floor. One advantage ofsaid hybrid device is the option of adjusting size to fit variousplaces. In one embodiment of the present invention, it is installed in asubmarine and in another embodiment it is installed at a sports ground.At public places expensive parts may be advised to keep unexposed. Inrelation to this advantage of the present invention it may be mentionedthat the showers described in US2011225722 and SE469413 both are limitedto cabin solutions. As such they are limited to more or less traditionalhousehold usage, and are not suitable for installation in e.g. asubmarine. The present invention, however, is a hybrid device which mayfind use in very different environments. Different examples are e.g. thetraditional household installation, in possible module systems or insubmarines as disclosed above. There are also very different possiblesystem or module types where the hybrid device according to the presentinvention may be incorporated. One example is in a combined system witha shower (hybrid device) and bath tub, where clean water may be reusedin a very economical way. In such a system, special valves and nozzlesmay have to be installed in the system. Another possible different useis as a standalone solution, with or without a cabin, where the hybridshower device is coupled to an external energy (heating) source andpossibly also an external water container. The latter solution may be aneffective embodiment of the present invention for use in e.g. developingcountries.

As mentioned above, the present invention may comprise a flow meter. Oneadvantage of said flow meter is ensuring a steady flow; this mayindicate filter condition, and this in turn may indicate the purity ofthe water. Further, in one embodiment of the present invention the flowis 9-20 L/min; in another specific embodiment of the present invention,the flow is about 15 L/min. Another advantage with the presentinvention, is receiving information from the flow meter. Thisinformation provides an indication about the amount of semi-contaminatedwater required to finish said nano-filter.

In one specific embodiment of the present invention, said hybrid devicecomprises at least one water quality sensor. Said sensor may bepositioned in contact with said filter system, but also other positionswithin the system may be of interest. Said water quality sensor may be aTOC sensor (Total Organic Carbon), a biosensor, a pH meter (measuringacidity or alkalinity) or an optical sensor, but also other kinds ofsimilar means are possible. In one specific embodiment of the presentinvention the water quality sensor is an conductive sensor, such as anelectrical conductive sensor.

In one embodiment of the present invention, said hybrid device comprisesa modified drain. Said modified drain collects the water used andfacilitates the stream of water towards the recycling loop and filtersystem or towards drainage. In one specific embodiment of the presentinvention, said modified drain comprises at least one sensor, indicatingthe water quality, as mentioned above, and wherein the hybrid device isarranged to redirect the water from recirculation to drainage when theat least one water quality sensor indicates the need thereof. Said waterquality sensor may be a TOC sensor (Total Organic Carbon), a biosensor,a pH meter (measuring acidity or alkalinity) or an optical sensor, butalso other kinds of similar means are possible. In yet anotherembodiment of the present invention, said nano-filter comprises at leastone sensor indicating the water quality. One advantage of said waterquality sensor is ensuring the user of a pre determined water quality.In one specific example, a user that has concerns or actual informationof a poor water quality, may allow all water to pass through the hybriddevice according to the present invention one round, before using thewater. Furthermore in one specific embodiment relating to the presentstatement, the design may be a filter system placed before the watercontainer, in process terms. The present invention is described as ashower concept but the hybrid device is to be seen as possible unit toincorporate in various equipment such as a sink, a toilet, a bathtub, adishwasher, a washing machine, but not exclusively. Also other methodsof application are thinkable. One specific embodiment is incorporatingthe device according to present invention close to the water inlet in ahouse. In this case, as is the case for also many other applications,the interaction between the filter quality sensor and a water qualitysensor is important. The filter sensor according to the presentinvention ensures a satisfactory operation of the filter system, and thewater quality sensor acts as a protector of the filter system so thatthe filter system is not subjected to a too contaminated water mixture.

In the present invention, when any of said sensors is indicating anissue, the hybrid device notifies the user and the system is redirectedfrom recirculation to drainage. Dependant on the embodiment, the systemnotifies where there is an issue in process terms. The system informsthe user if it is for example the pre-filter, the nano-filter or therecirculation pump that needs to be examined.

According to the present invention, said hybrid device comprises arecirculation loop. Said recirculation loop facilitates recirculation ofwater within the system. In its simplest design, said recirculation loopmay be said to constitute only piping/tubing. The design may vary andthe ability to recirculate water is the key feature of the recirculationloop according to the present invention. According to one embodiment ofthe present invention, said recirculation loop comprises at least onerecirculation pump. Said recirculation pump may be a two component pump,but other pumps are possible. In another embodiment, said recirculationloop comprises two recirculation pumps. One said recirculation pump,facilitates collecting water via said modified drain. The other saidrecirculation pump facilitates pressure management of water flow nearsaid water reservoir.

Furthermore, it should be noted that the water reservoir according tothe present invention may function as a buffer tank. Such a buffer tankmay act as a pressure equalizer or damper for the hybrid device systemso that pressure may be held reasonably constant in the entire system.

One advantage of the present invention is the option of bypassing therecirculation mode allowing all water to be drained. This provides theuser with a conventional shower experience. This may be useful if thehybrid device is intended for several users, and a few of the users havelittle faith in technology, or the system is temporarily malfunctioning.Either way the user is not left without a shower option. Further, if theuser is waiting for a service technician to repair, or exchange anypart, the user is not left without a shower option. The presentinvention provides the user with an economically, user- andenvironmentally friendly option to existing shower alternatives.

DETAILED DESCRIPTION

FIG. 1 shows one embodiment of the hybrid device 1 according to thepresent invention. According to this specific embodiment, the hybriddevice 1 comprises a recirculation loop 2, at least one filter qualitysensor 3, a filter system 4, nano-filter 5, pre-filter 6, flow meter 7,water reservoir 8, level sensor 9, modified drain 10, circulation pump11, at least one water quality sensor 12, and a flow through waterheater 13. A possible temperature gauge 14 is also shown.

FIG. 2 shows one example of a flow chart of the present invention.According to this example, the flow chart comprises: a hybrid device 1,a recirculation loop 2, at least one filter quality sensor 3,nano-filter 5, pre-filter 6, flow meter 7, water reservoir 8, modifieddrain 10, at least one water quality sensor 12, flow through waterheater 13. A possible temperature gauge 14 is also shown.

It should be noted that the hybrid device according to the presentinvention of course may comprise different standard components, alsohaving varied design, which are not explicitly mentioned. Examples ofsuch are one or more shower nozzles, different kinds of tubing, valves,etc. etc. Moreover, the design of the hybrid device may vary, and thepresent invention, as formulated in claim 1, should be seen as embodyingdifferent forms of the device.

The invention claimed is:
 1. A hybrid device, which is a shower that isadapted to function both as a recirculation shower and as an ordinaryshower, and allows purification and either recycling of water ordiscarding of water, wherein said hybrid device comprises: arecirculation loop which facilitates recirculation of water within saidhybrid device; a filter system comprising a nano-filter, at least onefilter quality sensor, and at least one pre-filter positioned before thenano-filter in process terms; a water reservoir connected to therecirculation loop, wherein the water reservoir is located on arecirculation loop water line between the nano-filter and a showerheadthat provides water to the shower, and wherein the water reservoir isfurther connected to a fresh water line configured to provide freshwater to the reservoir; and a modified drain having a first of at leastone water quality sensor arranged in the modified drain, the first waterquality sensor configured to indicate the quality of water in themodified drain, wherein the modified drain is adapted to, at least oneof, facilitate a stream of used water towards the recirculation loop andthe filter system for purification and recirculation, or discard theused water to a drainage system based on an indication of the quality ofthe water from the first water quality sensor.
 2. The hybrid deviceaccording to claim 1, wherein a first of the at least one filter qualitysensor is positioned upstream of the pre-filter in the recirculationloop and between of the modified drain and the pre-filter process termsin a single cycle of the process starting at the first filter qualitysensor.
 3. The hybrid device according to claim 2, wherein a second ofthe at least one filter quality sensor is positioned downstream of thenano-filter in the recirculation loop and between of the nano-filter andthe water reservoir.
 4. The hybrid device according to claim 1, saidhybrid device also comprising a flow meter in connection to thenano-filter in process terms.
 5. The hybrid device according to claim 1,said hybrid device also comprising one or more filter housing(s).
 6. Thehybrid device according to claim 1, said hybrid device also comprisingat least one level sensor within said water reservoir.
 7. The hybriddevice according to claim 6, said hybrid device also comprising twolevel sensors within said water reservoir.
 8. The hybrid deviceaccording to claim 1, further comprising a recirculation pump configuredto pump water in the recirculation loop, wherein the modified draincollects the water and with the aid of the recirculation pump, recyclesrinsing water via the recirculation loop, or discards water with highamounts of contaminants.
 9. The hybrid device according to claim 1,wherein the first water quality sensor is an electrical conductivesensor.
 10. The hybrid device according to claim 1, wherein the at leastone water quality sensor comprises a second water quality sensorconnected to the nano-filter.
 11. The hybrid device according to claim1, said hybrid device comprising a flow through water heater.
 12. Thehybrid device according to claim 1, wherein the nano-filter filters nanosize particulates.
 13. The hybrid device according to claim 1, whereinthe water reservoir is downstream of the nano-filter.